Secrets Beneath the Ice

Is Antarctica headed for a catastrophic meltdown? New evidence of ancient climate change may hold clues.
Airing December 28, 2011 at 9 pm on PBS
Aired December 28, 2011 on PBS

Program Description

Almost three miles of ice buries most of Antarctica, cloaking a continent half again as large as the United States. But when an Antarctic ice shelf the size of Manhattan collapsed in less than a month in 2002, it shocked scientists and raised the alarming possibility that Antarctica may be headed for a meltdown. Even a 10 percent loss of Antarctica's ice would cause catastrophic flooding of coastal cities unlike any seen before in human history. What are the chances of a widespread melt? "Secrets Beneath the Ice" explores whether Antarctica's climate past can offer clues to what may happen. NOVA follows a state-of-the-art expedition that is drilling three-quarters of a mile into the Antarctic seafloor. The drill is recovering rock cores that reveal intimate details of climate and fauna from a time in the distant past when the Earth was just a few degrees warmer than it is today. As researchers grapple with the harshest conditions on the planet, they discover astonishing new clues about Antarctica's past—clues that carry ominous implications for coastal cities around the globe.

DAVID
HARWOOD (Geologist, University of
Nebraska): We're going into
uncertain lands, uncertain future. How will the earth respond?

NARRATOR: Today,
a pioneering team is searching for answers with a bold new plan and a
revolutionary new machine.

TIM
NAISH: No
one has ever drilled through an ice shelf, and that presents these challenges.

NARRATOR: They
must drill down nearly a mile and more than 20 million years, deep into
Antarctica's ancient history. In this unforgiving place, it's never been done
before.

RICHARD
LEVY (ANDRILL Science Management Office): It's quite amazing, when you think about where we
are and what we're doing. Anything can go wrong at any minute.

NARRATOR: The
stakes are high because the secret to Earth's future lies buried in
Antarctica's past. Right now on Nova, Secrets Beneath the Ice.

It's
the coldest, windiest, driest and most desolate landscape on the planet, with
few permanent residents except penguins and seals. This frosty continent
appears locked in a perpetual ice age. A colossal cloak of ice covers almost
every inch of land, and in some places, the ice is so thick and so heavy it
depresses the earth's crust almost half a mile.

Some
people call it "Earth's freezer," but scientists call Antarctica "the ice."

RICHARD
LEVY: Antarctica plays a
fundamental role in the way the earth functions.

NARRATOR: For
polar researchers, Antarctica is a giant laboratory, more than one and a half
times the size of the United States and home to 90 percent of all the ice in
the world.

RICHARD
LEVY: Anything that happens
down here, anything that changes, will affect the rest of the world.

ROBIN
BELL (Lamont-Doherty Earth Observatory,
Columbia University): Most
people don't think that change in Antarctica matters to them, but when we look
at New York City and we look that it's in front of the ocean, it matters.

NARRATOR: What
would happen if all of Antarctica's ice were to melt?

ROBIN
BELL: If Antarctica melts, sea level goes up... all of
Antarctica melts, sea level goes up 12 stories in New York City.

ROB
DECONTO (Climate Modeler, University of
Massachusetts): Sea level would
rise by more than 150 feet, flooding most of the world's coastal cities,
displacing hundreds of millions of people. That would be a change that you
could see from space. The earth would look different.

NARRATOR: In
any case, even a loss of just 10 percent of Antarctica's ice would be
catastrophic.

ROBIN
BELL: It would raise the sea level over there in Manhattan
about 19 feet, right up along the edge.

ROB
DECONTO: Big
sections of Brooklyn would be under water. Certainly the Mediterranean and some
of my favorite cities, like Venice, would, would look very different.

STEPHEN
PEKAR (Geologist, Queens College, City
University of New York): Tens of
millions of people would have to be relocated.

DAVID
HARWOOD: It'd be almost a different
planet.

RICHARD
LEVY: If sea level changes and
the climate around the coastal regions change, it's going to affect the climate
where you live, it's going to affect the things you can grow, it's going to
affect how you live.

There may be a list of things in store that come as
a result of raising sea levels that we haven't even thought about yet.

NARRATOR: Could
this be our fate? Is Antarctica heading for a major meltdown?

If
so, it may happen over centuries, but it could already be starting, because the
climate is changing. And it's changing because burning fossil fuels has
increased the level of carbon dioxide in the atmosphere.

STEPHEN
PEKAR: Today, we have something that's
completely manmade. And that is the addition of carbon dioxide being put into
the atmosphere by humanity, by us.

NARRATOR: Carbon
dioxide is a "greenhouse" gas: it prevents the sun's heat from escaping.

STEPHEN
PEKAR: I'm in the Brooklyn Botanic Garden
in a greenhouse. Greenhouses, they are basically like heat motels, heat motels
where the sun's rays can come in, and they get trapped inside the greenhouse.
They can't get out.

NARRATOR: So,
like glass in a greenhouse, gasses like carbon dioxide trap solar energy in our
atmosphere. But now, those levels are increasing.

STEPHEN
PEKAR: The result is that our earth is now
warming up, and the ice is melting, both in Antarctica and the Arctic.

ROBIN
BELL: In the north, there's two clear signals. In the
Arctic Ocean, you have lots of floating ice...and sticking around through the
summer. That's one sign of it getting warmer. The other sign is the edges of
the Greenland ice sheet are changing.

NARRATOR: And
the loss of Greenland's ice is now speeding up. In August 2010, an iceberg four
times the size of Manhattan broke off the edge of Greenland. But Antarctica has
nearly 10 times as much ice as Greenland, and in the past decade alone, rising
temperatures have caused giant pieces of coastal ice to shrink or crumble.

Polar
researchers fear that this could be just the beginning of a chain reaction. But
have Antarctica's ice sheets ever collapsed before? That's what an
international team of geo-detectives wants to find out.

RICHARD
LEVY: We actually have some
water, some melt water, coming out of the ice.

NARRATOR: To
get a more precise picture of Antarctica's future, they plan to dig deep, for
answers in the past, with a giant drill.

DAVID
HARWOOD: By drilling into areas around
Antarctica, we're able to perceive a history that has an impact for where we're
headed as a planet.

NARRATOR: Antarctica
was not always locked in a deep freeze. A hundred and sixty million years ago
it was part of an enormous supercontinent closer to the Equator. At the time,
Earth was much warmer than today, and fossil evidence suggests this giant
landmass was a tropical habitat, teeming with dinosaurs. Eventually, the
supercontinent broke apart and Antarctica drifted south.

As
Earth was getting colder, falling carbon dioxide levels and powerful ocean
currents cooled the isolated continent even further. And then, around 34
million years ago, ice slowly began to form. It would take millions of years
for Antarctica to finally lock into a deep freeze, and during that time it
remained warm enough for plant life to survive.

Evidence
of that was recently unearthed in a relatively ice free valley in the interior.
Here, geologists Alan Ashworth and Adam Lewis find a remarkable fossil.

ADAM
LEWIS (North Dakota State University): That leaf fell into the mud maybe 20 million years
ago.

ALLAN
ASHWORTH: That may be the best leaf yet.

ADAM
LEWIS: That's a sweet leaf.

ALLAN
ASHWORTH: Yes it is. It may be the best
one.

NARRATOR: And
then, they find something extraordinary.

ALLAN
ASHWORTH: This is like a peat moss. And
then if we take, tease some of this out, they're like they're freeze-dried.

NARRATOR: Under
the microscope, these brittle mosses are in pristine condition. These moss
fossils are not rock, but actual plant tissue, the last vestiges of vegetation from a time when
Antarctica was still warm.

They
were found under a layer of volcanic ash that dates back millions of years.

ADAM
LEWIS: This is the original moss tissue. And even the cells are preserved in
these fossils.

NARRATOR: These
plants were flash frozen when Antarctica plummeted into a deep freeze that
preserved them until today.

ADAM
LEWIS: It's mind-boggling. The only way is to say the climate remained very,
very cold, it remained very, very dry, and it did not warm up for even
relatively short periods of time in this location. Otherwise, these things are
gone.

NARRATOR: But
now, as Earth is heating up, what will happen to Antarctica? Will it melt,
raising sea levels all over the planet? How sensitive is this frozen land to
the temperature changes we currently face?

But
before researchers can investigate in Antarctica, last minute testing is taking
place here, over 2,000 miles away, in the countryside of New Zealand, with a
brand-new drill.

ALEX
PYNE (Antarctic Marine Geology Research
Centre, New Zealand): Yeah. It's
a shakedown. We've got a few leaking connections and things that don't quite
fit as well as they need to. A little bit of modification's requiredâ¦pretty
common with a brand-new piece of equipment.

NARRATOR: Weighing
in at a whopping 40 tons, this mechanized marvel is as heavy as a humpback
whale and just as large. Towering some five stories high, the giant rig will
soon dwarf everything in sight except the ice.

ALEX
PYNE: This will be the largest drill rig in Antarctica
that's used on land.

NARRATOR: And
this mammoth rig can drill in more than one place. That's because it's mounted
on a sled.

ALEX
PYNE: I think it probably is unusual. All of the equipment
is on sledges, so in Antarctica we pull it all with big bulldozers.

NARRATOR: It's
been specially designed to drill from the ice, in order to extract hidden
secrets from beneath Antarctica itself.

This
unique multi-national enterprise is called ANDRILL, the Antarctic Drilling
project. For team leader David Harwood, it's a dream come true.

DAVID
HARWOOD: As a scientist, there's a passion
that comes in trying to figure it out, trying to identify what has been the
past history of the ice sheet and wondering what the future might hold.

NARRATOR: Soon,
the giant drill will be dismantled and readied for a long sea voyage, but now,
the ANDRILL team gathers at Christchurch, New Zealand for the six-hour flight
to Antarctica in a C-17 cargo plane, jam-packed with people and gear.

Their
flight passes over the Transantarctic Mountains, which divide the continent
into two regions, with colossal glaciers, called ice sheets, blanketing both.

The
giant east Antarctic ice sheet is ten times the size of the west. It's frozen
firmly to bedrock, high above the sea, and in some places the ice towers almost
three miles into the sky.

The
smaller west Antarctic ice sheet is less stable. That's because it rests on
land well below sea level, and it extends hundreds of miles over the ocean in
floating ice shelves.

It's
likely east and west Antarctica will respond very differently to a warming
world.

The
ANDRILL team touches down in the west, on an icy runway at McMurdo Station, the
largest U.S. research base in Antarctica. As David Harwood and Richard Levy step
out onto the ice, the first thing they notice is the weather.

RICHARD
LEVY: Breeze is a bit chilly,
but it's beautiful. It's good to be back.

NARRATOR: It's
October, springtime, and it's minus-20 degrees.

RICHARD
LEVY: It's the earliest I've
ever been down to Antarctica, and it's very cold. When the wind picks up, it's
rather an unpleasant place to be working. When the wind isn't blowing and the
sun's shining, it's actually really quite nice, but very cold.

NARRATOR: But
even a sunny afternoon can turn nasty at a moment's notice.

Guy
in shorts: It's a beautiful
day!

NARRATOR: McMurdo
Station has been a vital hub of research for over half a century. What began as
a tiny outpost has, over the years, grown into a small town. McMurdo houses a
population of 200 people year-round, but during the research season, it becomes
home base for over a thousand.

Every
year, McMurdo supports scores of research projects, providing lab facilities,
food and supplies, and survival training for teams of scientists who will head
out to remote field camps. This season, those numbers include the ANDRILL team
of over 50 technicians and researchers from the U.S, New Zealand, Germany and
Italy.

ANDRILL
is funded by their governments and the National Science Foundation.

RICHARD
LEVY: There's probably a week,
at least, of work in McMurdo, where we have to get all of our gear sorted out,
getting everything we need in order to be able to work and survive out in the
field.

NARRATOR: As
they gather supplies for more than a month on the ice, one item is in high
demand.

LAURA
LACY (ANDRILL, University of Nebraska):
Sugar actually heats your body. It gives
you quick energy, especially if you're, like, freezing. And we expect to be
very cold.

We
don't really know how much chocolate is enough. We can take up to 560 candy
bars. But Iâm looking at this, and I'm already getting queasy. I don't know if
I can eat this or not.

TIM
NAISH: Hey, David.

NARRATOR: As
ANDRILL researchers prepare for life in the field, they join hundreds of other
scientists fanning out across Antarctica. And many are focused on the same
question: could Antarctica be headed for a meltdown?

ADAM
LEWIS: Over here is Mt. Boreas.

DAVID
HARWOOD: We're going to have a lot of
scientists working together and challenging each other's theories, challenging
what we know. As a community, we're going to find the answers.

NARRATOR: But
the continent won't give up its secrets easily. The stark beauty of Antarctica
masks a treacherous nature. More than 70 percent of all the fresh water in the
world is harbored here, but most of that water is frozen. And with less
precipitation than the Sahara, Antarctica is the driest desert on Earth.

Raging
winds, of up to 200 miles per hour, sometimes blast the frozen terrain, where
temperatures can drop to a hundred degrees below zero. Only during the short
Antarctic summer can most researchers gather precious scientific data from this
giant mystery continent.

A
four-hour flight and 400 miles from McMurdo, is the center of the west
Antarctic ice sheet, and for one team, this is the best way to find out about
the past.

KENDRICK
TAYLOR (Desert Research Institute):
This is the side of a snow pit. It's a
thin wall between two pits. The other side is open, so the light can shine
through the wall. You can really see the different layers in the pit. So this
is one year's worth of snow accumulation, and there's a second year's worth of
snow accumulation here, below it: two years of record, right here in the snow
pit. But, of course, we want to go back a lot further in time than that. In
order to do that, we can't just use shovels and chain saws like we did here, so
we have to use a drill.

NARRATOR: Ken
Taylor's team is drilling through ice. Their goal is to gather samples from the
nearly two-mile-thick west Antarctic ice sheet. And the deeper they go, the
farther back in time they travel.

REBECCA
ANDERSON(Desert Research Institute )We're
at about 480-meters deep right now. This was right around the time when Jesus
lived. It's right about zero A.D., right when B.C. years turned into A.D.
years.

NARRATOR: These
ice cores contain tiny bubbles of ancient atmosphere that were trapped each
year as the snow was compressed into ice.

KEN
TAYLOR: Nice bubbles in this one. That's ancient air in there. When we crush
samples like this, that'll get the gas out of there. We can sample the ancient
atmosphere. We can also get a record of how things like temperature and sea ice
changed in the past. And by combining these different records, we can
understand how the climate system has operated in the past.

NARRATOR: But
the ice record, valuable as it is, only goes back about 800,000 years, a tiny
fraction of geologic time. To get a more complete picture of Antarctica's
climate history, you have to drill farther back in time.

And
that's what the ANDRILL team is trying to do. They want to paint a
picture of Antarctica as it changed from warm to cold, millions of years ago.
In order to do that, ANDRILL will have to drill deep into the earth. But finding
the right location is a major challenge on a continent covered by ice. And even
in those few places where the ice has receded, it's still not easy.

ANDRILL's
David Harwood and Richard Levy are searching for places to drill. But as they
fly over a field of rubble, they see that gathering evidence for a
chronological history is not possible here. Something has stirred things up.
And that something is the ice itself.

That's
because ice moves. For tens of millions of years, glaciers have slowly scoured
the land, gobbling up rocks and debris and spreading them all across the
landscape in random order.

DAVID
HARWOOD: This we call "glacial
paleontology," some call it "garbage pile paleontology" âcause we are looking
and sorting through these moraines to try and get pieces of information that
the ice sheet has brought to us.

NARRATOR: A
moraine is the chaotic accumulation of rocks and debris deposited by glacial
movement.

RICHARD
LEVY: This one, here, has an
abundance of shell fossils.

NARRATOR: This
shell, brought here by a glacier, comes from a time when the continent was
warmer and water ran through these valleys.

This
landscape is a treasure trove of Antarctica's climate history, but the ice has
scrambled all the clues.

DAVID
HARWOOD: We're looking at a jigsaw puzzle.

NARRATOR: Yet
there's one place where the evidence remains undisturbed, intact. That's in the
sea floor beneath the Antarctic ice shelf, where the glacial movement has also
deposited layer after layer, in chronological order.

DAVID
HARWOOD: Drilling gives us an opportunity
to get a, get a serial history in time, back in time. Each layer goes back in
time. We know a rock above is younger than a rock below, so we can put it into
a history.

NARRATOR: The
ANDRILL team aims to drill through the Antarctic ice and the sea below. Then,
like a hollow tube thrust through a layer cake, they'll bore deep into the
ocean floor, in order to recover millions of years of rock and mud that trace
Antarctica's climate history.

Even
after ice began to form in Antarctica, around 34 million years ago, the
continent remained warm enough for plant life to survive, a lot like areas of
New Zealand, today, where ice can be found bordered by trees and plants.

But
when did Antarctica plunge into a solid deep freeze? And how did it happen? Was
it gradual or abrupt? Will the story of how Antarctica changed from greenhouse
to icehouse reveal new clues about the continent's climate future and our own?

The
ANDRILL team will spend the next few weeks searching for drilling locations
from the surface of the ice, but David Harwood remains focused on what lies
below.

DAVID
HARWOOD: When I'm driving across there,
I'm always thinking about what's beneath us. I'm over about 15 feet of ice, and
over that, I'm over about 1,500 feet of water, and the sediment's below that.

NARRATOR: Here,
at the bottom of the world, the sun never sets in the summer, and as night
blends into day, the work begins in earnest.

The
team heads out to McMurdo Sound, a place where the ocean freezes annually,
creating a precarious platform of floating sea ice that will only last a few
months.

DAVID
HARWOOD: We're standing, right now, in the
southern part of McMurdo Sound. Seasonally, this region will break out to sea
ice that we're standing on and will melt out. It's now strong enough, perhaps
20 feet beneath us is the thickness of ice, and then 1,500 feet of water
beneath us, as well.

NARRATOR: Just
to be sure they're in the right place, the team blasts powerful sound waves
through the sea ice and into the seafloor below. The result is a sonic street
map of layer after layer of rock and mud, each one representing a different era
of the past.

DAVID
HARWOOD: By looking in the past, we can
maybe project into the future. How dynamic has been the behavior of the ice
sheets. Have they been static and slowly changing? How active of a player have
they been?

NARRATOR: Finally,
it's time to tow the giant drill out onto the ice. To ensure that the weight of
the rig isn't supported by the sea ice alone, divers attach flotation devices
to the drill pipe. And at the end of that pipe is a whirling tool with a unique
cutting edge, a drill bit made of diamonds, that can bore through almost
everything in its path.

DAVID
HARWOOD: The diamond core system that we
have, it's almost like melting the core down through the rocks, just cuts
through whatever's there. If you hit a big boulder, you'll just end up with a
cylinder of that boulder, and it'll just keep going.

NARRATOR: Now
the real drilling begins. There's not a minute to waste, because the Antarctic
research season is so short. The crews work around the clock to recover cores
of rock that trace Antarctica's ancient past.

The
powerful drill bores down over three quarters of a mile, bringing up 12 feet of
core at a time, each foot averaging a thousand years of climate history.

It's
an astonishing feat.

RICHARD
LEVY: It's quite amazing, when
you think about where we are and what we're doing. We've got a drill rig, a
60-ton to 90-ton—with all the equipment on it—the drill rig,
sitting behind us, on eight meters of sea ice, above 380 meters of water. And
then we're drilling down into the seafloor below that with a 3 to 4 inch
diameter pipe that's turning round and around like a piece of spaghetti hanging
down through the water and into the ground. And it's wobbling around a bit, and
we're turning around and bringing out core from deep from within the earth.

Anything
can go wrong at any minute with this process.

NARRATOR: And
all too soon, it does.

Sometimes
even a drill bit made of diamonds can run into trouble.

ALEX
PYNE: We haven't been getting particularly good quality
core. And we're suspecting that the drill bit has been damaged. In places it's
a little bit narrower than it should be for the size of the diamond bit. And
that means we have to pull all of our pipe out—about 17,000
meters—and replace the bit and then put the pipe back down the hole. And
that's going to take us about 24 hours to 36 hours.

NARRATOR: Removing
and replacing nearly a mile of pipe is no easy task, especially when it's your
job to change it all out, piece by piece. But for other members of the ANDRILL
team, it's a welcome break.

MICHELLE
BRAND-BUCHANAN: Suppertime! Come and get
it!

NARRATOR: In
an extreme environment like Antarctica, nobody's on a diet. Your body is
working so hard to stay warm, packing away 6,000 calories or more a day is not
an indulgence, it's a necessity. And because Antarctica is drier than the
hottest desert, dehydration is a constant concern.

And
keeping the drill up and running is another. Finally, after a day and a half of
hard work, the new bit is in place and drilling is back on track.

They
recover a 12-foot length of core. Wrapped in a protective cover, workers
carefully carry it back to the lab to be examined.

When
they crack it open, it's in perfect condition. This mud and rock is more
valuable than gold, because each core is a time machine.

DAVID
HARWOOD: We're currently down at a depth
of about 440 meters.

NARRATOR: That's
about a quarter mile down, corresponding to a time, at least 15 million years
ago, when Antarctica was still warm.

As
the cores are recovered, each section is sliced lengthwise, X-rayed and scanned
in labs at the drill site and back at McMurdo.

MATT
CURREN (Curator, Antarctic Marine Geology
Research Facility): These cores
came out of the ground three days ago; they were split yesterday; they were
imaged yesterday. The sedimentologists worked the nightshift, 12 hours,
describing these cores millimeter by millimeter, looking at the color, size
ratios, any kind of structure they see in a core, trying to understand how
these sediments were deposited.

NARRATOR: Each core tells a story, depending on its texture,
color and contents, and some of those stories are spectacular.

DAVID
HARWOOD: We're seeing some macrofossils,
some large shells.

NARRATOR: These
shells are evidence of warmer times, even as Antarctica is icing up.

MARCO
TAVIANI (Institute of Marine Science,
Italy): This is one ofâ¦the most
spectacular fossil found was in ANDRILL this season. This is a scallop. This
kind of scallop simply do not live in extreme polar waters.

NARRATOR: And
there are other clues, some of them nearly invisible. Hidden inside these cores
are shells of microscopic algae called diatoms. For ANDRILL climate detectives, these tiny diatoms
create a highly revealing picture of the past, because not all
diatoms are alike. Some species are adapted to colder conditions, while others
flourish in warmer waters.

DAVID
HARWOOD: We use them as biological
markers, to be an index of different environmental conditions: cold or warm,
frozen waters or open ocean waters.

NARRATOR: Again,
the ANDRILL team examines the cores from around 15-million years ago. They find smooth green sands, containing diatoms
that thrived in relatively warm water, confirming this was a time
before Antarctica finally froze over.

DAVID
HARWOOD: This is a very well defined warm
period, iceberg-free waters, open waters where diatoms are growing and
thriving. You can see this persisted for quite some time.

NARRATOR: A
picture is beginning to form of a long period of transition, starting
34-million years ago, when a cooling climate led to the formation of ice. But
even so, conditions remained relatively mild.

But
when did Antarctica finally slip into a deep freeze? The answer lies in cores
from around 14-million years ago. Instead of smooth and green, these cores are
rocky and gray, and some contain diatoms that thrived in cold glacial waters.

This
amazing discovery reveals a rapid change from cool to frozen. It fills in what
has always been a blank page in Antarctica's climate history.

Next
season, they'll attack another crucial question: after Antarctica froze
14-million years ago, did the ice ever melt or has it remained a frozen
wilderness right up until today?

That
answer will have to wait. Cracks in the sea ice tell the team it's time to
return to base.

CECE
MORTENSON (Raytheon Polar Services): We've seen the ice breaking quite a bit in the last
month, but it's not broken in any further south than it is right now.

RICHARD
LEVY: We can only be on this
site for so long before the sea ice starts to melt, before the conditions
change and, for safety reasons, we have to get off the sea ice.

NARRATOR: The
precarious sea ice of west Antarctica may come and go with the seasons, but
what about the giant east Antarctic ice sheet? A mountain of ice so high, it
covers mountains.

ROBIN
BELL: This is like an M.R.I. of the ice sheet. Some places
it's really thick, two miles thick and pretty flat and boring. But then there
are other places where what we discovered were hidden mountain ranges the size
of the Appalachians, but totally hidden by the huge east Antarctic ice sheet.

NARRATOR: There's
10 times as much as ice in the east as in the west, but a small portion of the
east has almost no ice at all. It's an unearthly location that defies the very
image of Antarctica. These are the dry valleys: cold, barren, and except for a
few scientists, almost completely devoid of life. The landscape is so alien
that NASA has used it as a test site for space programs.

DAVE
MARCHANT (Glaciologist, Boston University): It's a fantastic place. You can't find this
anywhere else on Earth. Its closest analog is the surface of Mars.

NARRATOR: Mullins
Valley is the ultimate remote field camp. It serves as home base for a
pioneering band of glaciologists, led by Dave Marchant.

Marchant
and his team are conducting research the rugged, old-fashioned way. They'll
live in tents and won't be picked up for two months. They need to be
self-sufficient, and for the most part, they like it that way.

MAN:
Burritos!

DAVE
MARCHANT: You come out here, you have no
contact with the outside world—no email, no real telephone
contacts—so you can totally immerse yourself in the science, and that
allows you to think 24 hours a day about what you're doing. The other side of
that is, is that you have no idea what's going on outside.

LAURA
ROBINSON (Woods Hole Oceanographic
Institute): At the beginning of
the season, I didn't like it when you would freeze and the frost would form on
the outside of the sleeping bag, but it's warmed up now, and it's a little bit
more comfortable in the morning.

DAVE
MARCHANT: Small setups like we have, which
are helicopter-supported, are isolated. They're among the most isolated in the
region, and as a result, we have to check in daily with McMurdo.

I'm
trying to heat the batteries up so we can get a signal out. Right now there
appears to be no satellite covers and the batteries are a little bit cold, so
I'm trying to warm it up. Sometimes, you have to contort your body in various
ways to get the signal. Nah, we don't have enough signal yet.

Here
we go. We got something that might work.

Mac
ops this is Gulf 054 Mullins Valley. We have all seven on board, and all is
well. Over. Ughâ¦ lost transmission.

This
valley holds an incredible record. This area is so dry and so cold, that the
landscape is pristine. The rocks we see here are millions of years old.

NARRATOR: Marchant
believes that little has changed here for millions of years.

DAVE
MARCHANT: What, to me, is exciting is that
we're walking on an ancient landscape. Imagine living 10 million years ago, and
if you were in Antarctica, this is what you'd see, exactly as it is today,
hardly modified at all.

NARRATOR: But
when Marchant's team drilled beneath this rubble, they found something totally
unexpected: a hidden glacier that extends hundreds of feet below the surface.

NARRATOR: The evidence comes from volcanic ash. The dry
valleys are surrounded by extinct volcanoes that erupted millions of years ago.

DAVE
MARCHANT: We're finding ash deposits on
top of the ice. The ash dates are coming back as old as 8,000,000 years.

NARRATOR: And, according to Marchant, this volcanic ash shows
that this hidden glacier, once frozen, has never melted.

DAVE
MARCHANT: This volcanic ash that erupted
from a volcano and has been sitting here for millions of years, it shows no
chemical alteration, which you'd expect if there were any amount of liquid melt
water over that duration. The fact that it's dry and pristine tells me it's
always been here, which is incredible.

NARRATOR: Equally
astonishing, and just 300 miles away, there appears to be a completely
different picture.

Exploring
east Antarctica, closer to the South Pole, ANDRILL's David Harwood found leaf
fossils and pieces of wood. Surprisingly, according to Harwood, these date to a
relatively recent time, when Antarctica was not only warmer than today, there
were plants and trees.

DAVID
HARWOOD: This is a piece of southern
beech. This wood is not fossilized, in the sense that it's petrified. It could
still burn. To find the wood and leaves together, it is pretty phenomenal. It's
really phenomenal for Antarctica, for, particularly for Antarctica in this time
period, about 4,000,000 years ago.

NARRATOR: This
season, the drill is set up to find evidence of what happened in Antarctica
during this period, 3- to 5,000,000 years ago. It's a time known as the
Pliocene.

ROB
DECONTO: Now,
what's important about that is that the Pliocene was globally warmer than
today.

NARRATOR: The
same temperatures as our Earth may be headed for at the end of the century, if
climate change predictions are correct.

TIM
NAISH: If we go back 3- to 5,000,000 years
into the geological past, we know that there was a time when Earth's climate
was warmer than it is today, perhaps by three to four degrees. So, it's the best
example we have of where the climate's heading in the next hundred years.

NARRATOR: The
drill's new location is on the giant Ross Ice Shelf, which extends out and over
the ocean. It's the largest ice shelf in the world, and it helps hold back the
massive Antarctic ice sheet from flowing into the sea.

ROB
DECONTO: These ice
shelves are very important, because what they do is hold back the flow of ice
that's actually trying to flow out into the ocean. We call that buttressing.

NARRATOR: If
warming oceans cause the Ross Ice Shelf to break up and melt into the sea, the
west Antarctic ice sheet would eventually follow right behind.

The
ANDRILL team is looking for the answer to a critical question: when Earth was
warming during the Pliocene, what happened to the ice? Did the Ross Ice Shelf
melt, taking the giant ice sheets with it?

Drilling
on an ice shelf brings with it a unique set of technological challenges,
including constant problems with mud and water.

Unlike
drilling through sea ice, which is just 26 feet thick, the ice shelf here is
400 feet.

ALEX
PYNE: We're looking at at least doubling or trying to
double our capability below the seafloor and penetrate to a thousand meters or
better into the seafloor.

NARRATOR: But
that's only the beginning.

TIM
NAISH: No one has ever drilled through an ice shelf, and
that presents these challenges. The ice shelves, they float up and down with
the tide, so you've got to deal with a vertical elevation change. They move
sideways, they âflow,' so, eventually, your drill pipe is going to get bent.

NARRATOR: Can
the drill bore through a thick layer of ice that's constantly moving, without
breaking or getting yanked out of the seafloor?

To
confront this unique challenge head-on, the ANDRILL team invents a new tool, a
hot-water drill. This marvel of engineering is a moving ring of heat that
blasts jets of steaming water to melt a wide hole so the drill can operate
freely through 400 feet of shifting ice.

And
once again, time is so precious the team must work around the clock, not only
retrieving cores, but also analyzing them.

MATT
CURREN: We're laying
out the cores in the proper sequence, from top—the very highest point in
the core—all the way to the very lowest point of the core, here.

NARRATOR: An
80-foot core that dates back about three million years is closely examined. It
contains microfossils of single-celled animals known as "forams." They're from
the crucial warm period called the Pliocene, and these tiny shells are precise
indicators of ocean temperature.

GAVIN
DUNBAR (Antarctic Marine Geology Research
Centre, New Zealand): So, these
guys are the size of a grain of sand. Because the same species has lived
through time, we can use the chemistry of modern examples to allow us to
calibrate, if you like, the chemistry of ancient examples.

TIM
NAISH: What Gav's doing here is he is measuring the amount
of two metals, magnesium and calcium, that are in the ocean and get
incorporated into the shell of the foram when it's growing in the ocean. And
that process is dependent on the temperature of the ocean. So, we know the
magnesium, we know the calcium, we can determine the temperature of the ocean
at the time that foram lived.

NARRATOR: And
because of that, ANDRILL researchers can now calculate Antarctic water
temperatures during the Pliocene.

TIM
NAISH: What this is telling us is that temperatures were
three to four, perhaps five degrees above present.

ROB
DECONTO: Even just
one degree rise in ocean temperatures in the waters surrounding Antarctica will
attack and begin to melt the ice shelves from below, very quickly.

The
air temperatures will stay cold enough to keep things frozen at the surface,
but what we're worried about is the ice being attacked from beneath, not from
above.

NARRATOR: And
the cores reveal this is what happened during the Pliocene, when global climate
was warming. But they display even more change than expected, revealing not
only a patchwork of glacial rubble, but also smooth mud from open seas,
indicating that ice both froze and then melted many times.

ROSS
POWELL: There's a really important change
right here. This interval shows us quite a dramatic change in the environment.
There was ice and there was no ice.

GREG
BROWN (Institute of Geological and Nuclear
Sciences, New Zealand): The ice
sheet has gone backwards and forwards; it's advanced and it's retreated.

NARRATOR: As
they examine core after core from the Pliocene, they continue to see surprising
signs of change.

TIM
NAISH: The results of the drilling are simply spectacular.
They give us a picture of a dynamic ice sheet coming and going regularly, more
than 60 times.

What
we're seeing in this record is telling us that Antarctica is not just a benign
spectator, it's a player.

NARRATOR: What
this means is while it was generally warm during the Pliocene, there were also
brief periods of cooling. And the ice was exquisitely sensitive to even small
changes in climate. Just a few degrees could tip the scale from ice to no ice.

So,
what's in store for our future? As Earth continues to warm, how much Antarctic
ice will melt, and how high will sea levels rise?

The
ANDRILL scientists turn to computer models by Rob DeConto and Dave Pollard.

ROB
DECONTO: We
developed these climate models based on our best understanding of the physics
of the climate system and, in this case, ice sheets.

NARRATOR: And
now, information from ANDRILL is added to the climate model.

ROB
DECONTO: This is a
computer model simulation of the Antarctic ice sheet over the last several
million years and covers a good chunk of the interval that was recovered by the
ANDRILL sediment core. So, we're looking for the same kind of behavior in our
models that we're seeing in the geological record.

NARRATOR: As
the model simulates the warming periods of the Pliocene, all of the ice shelves
disappear, followed by the entire west Antarctic ice sheet and edges of the
east. And as temperatures change, the ice refreezes and melts again and again.

ROB
DECONTO: And
that's important because the changes in the ice sheet that we're seeing here
reflect pretty significant changes in sea level.

NARRATOR: According
to DeConto's model, sea levels rose about 23 feet during the Pliocene.
Temperatures back then were three to five degrees higher than now, just what's
projected to take place by the end of the century, but there's a lag time in
the way ice responds that may delay the impact for hundreds if not thousands of
years.

Regardless,
coastal cities all over the world would be at risk, potentially displacing
millions.

ROB DECONTO: We
would be remapping places like Boston and New York and the Bay Area. Not to
mention, of course, places like Louisiana, Miami, New Orleans, of course.

NARRATOR: But
even that might not be the worst-case scenario.

TIM
NAISH: Things were very similar to today in terms of our
climate.

NARRATOR: Tim
Naish brings Rob DeConto to New Zealand to look at a possibility that's even
more frightening.

ROB DECONTO: This is the first time I've seen the actual direct
evidence for what the models are doing.

TIM
NAISH: We're seeing a deepening sea level rise, up through
here.

We're
going to look at some rocks that are the same age as rocks withdrawn in Antarctica
that give us the record of global sea level changes.

NARRATOR: Here,
along the Rangatikei River, tectonic forces have raised the land, and the river
has cut into the earth, to expose layer after layer of sediment that once was
the seafloor.

What
they find are shells dated to the warming era of the Pliocene. These shells
provide a way to chart sea level in the past, because some of these species
still exist today.

TIM
NAISH: Many of these shells you see in here actually live
today. So they live around the coastline, and we know the water depth they live
in today. So, by breaking them out of these rocks and identifying them, we can
say the depth they were living over 3,000,000 years ago here.

NARRATOR: Because
these shellfish live on the seafloor and can only survive in water at specific
depths, they suggest that sea levels in the Pliocene were much higher than even
the computer models predict.

TIM
NAISH: This is really it, Rob. This is where we would say
we have the evidence for global sea level being up to as much as 20 meters
above present.

NARRATOR: That's
over 60 feet! In order for sea level to have risen that high, an enormous
amount of ice must have melted. And this raises a startling possibility: that a
large part of the vast east Antarctic ice sheet melted along with the west. And
if it melted once, could it melt again?

ROB
DECONTO: That
could be a very bad thing, because that would actually produce a contribution
to future sea level change that we really haven't been thinking about.

NARRATOR: This
presents an even more dangerous and unpredictable picture of Antarctica.

ROBIN
BELL: What's been surprising is even geologists thought
that glaciers and ice sheets were these large static features, which we would
never really see change in our lifetime, but glacial processes are no longer
quite as glacial. Things are moving faster than we had thought.

ROB
DECONTO: In the
next five years, greenhouse gas levels will be like they were in the Pliocene.
But we're not just going back to the Pliocene. Some of the projections put CO2
levels at twice the concentrations of the Pliocene by the end of the next
century. We're essentially going back to the time of the dinosaurs, when there
was very little ice on the planet and there were forests covering Antarctica.

NARRATOR: And
signs of change are already here.

Scientists
were completely caught by surprise when, in 2002, the Larsen Ice Shelf
shattered apart, without warning, in just a few weeks.

And
today, the Wilkins Ice Shelf, a block of ice approximately the size of
Connecticut, barely hangs on.

DAVID
HARWOOD: I would say it's, it's inevitable
that west Antarctica will disappear. How long it will take east Antarctica to
engage is something that's, that's not yet known.

NARRATOR: In
the coming years, the ANDRILL team will continue to explore Antarctica's
climate history, in order to gain valuable insight into Earth's future.

With
each new core, we gain new knowledge about a continent that's always been
shrouded in mystery. But its fate remains very much tied to our own.

Office of Polar Programs
Tom Wagner
University of Nebraska State Museum
Judy Diamond
Andrill Science Mgmt. Office
Frank Rack
Laura Lacy
Peter Webb
Antarctic Research Centre
Florida State University
Lamont-Doherty Earth Observatory
University of Massachusetts
North Dakota State University
Brooklyn Botanic Gardens
Penn State University
Peter West
Patricia Jackson
Mark Buckley
Valentine Kass
Mike Farrell
David Feingold
Joe Turco
Tim Svoboda, NET Television
Prem Paul
Thanks to the staff of Raytheon Polar Services at McMurdo Station who make it possible for scientists to conduct research in Antarctica.

Major funding for "Secrets Beneath the Ice" is provided by The National Science Foundation.

Additional funding for "Secrets Beneath the Ice" is provided by the Earth Science program at NASA.

National corporate funding for NOVA is provided by Cancer Treatment Centers of America and Farmers Insurance.
Major funding for NOVA is provided by the David H. Koch Fund for Science, the Corporation for Public Broadcasting, and PBS viewers.